A catalyst-free method for the highly regioselective hydrated ring-opening and formylation of quinazolinones was developed. This reaction realized the direct arylation of two nitrogen atoms on quinazolinones and realized the regioselective ring-opening of quinazolinone and subsequent acylation of methyleneamine through the nucleophilic addition of a water molecule to an imine carbon atom. It showed reasonable functional group compatibility and provided one-pot access to a variety of N -arylformyl derivatives in moderate to excellent yields.